Motorists are being told to be on alert after the driver of a fake police car with flashing blue lights and a siren tried to pull a moped rider over in Stoke-on-Trent.
The black car, possibly a Ford Mondeo or Focus, approached the moped in Blurton on Monday, police said.
The driver of the vehicle, which has lights set into its front grille, claimed to be a police officer.
The vehicle was also seen in Longton, Fenton, Hartshill and on the A50.
Staffordshire Police force is advising people not to stop in a secluded spot if they are uncertain about being pulled over on the road.
It suggest drivers should signal to show they have seen the vehicle, proceed to a public place and keep doors locked and windows closed until they see a warrant card.
Anyone who has seen the vehicle, which has been seen to overtake other vehicles with its lights flashing, or has any information or dash-cam footage is asked to contact Staffordshire Police.